1. Field of the Invention
This invention relates to automatic power transmissions providing a plurality of gear reduction ratios, such as automatic mechanical transmissions, and, in particular, to control systems and methods therefor. More particularly, the present invention relates to control systems and methods for automatic transmissions wherein gear selection and shift decisions are made and executed based upon measured and/or calculated parameters such as vehicle and/or engine speed, throttle position, rate of change of throttle position, rate of change of vehicle and/or engine speed and the like.
2. Description of the Prior Art
The use of automatic transmissions of both the automatic mechanical type utilizing positive clutches and of the planetary gear type utilizing frictional clutches is well known in the prior art as are control systems therefor. Electronic control systems for automatic transmissions wherein gear selection and shift decisions are made based upon certain measured and/or calculated parameters such as vehicle speed, engine speed, rate of change of vehicle speed, rate of change of engine speed, throttle position, rate of change of throttle position, full depression of the throttle (i.e. "kickdown"), acutation of the braking mechanism, currently engaged gear ratio, and the like are known in the prior art. Examples of such automatic transmission control systems for vehicles may be seen by reference to my allowed copending U.S. patent application Ser. No. 190,512 filed Jan. 24, 1978 and entitled Mechanical Automatic Transmission, now U.S. Pat. No. 4,361,060 issued Nov. 30, 1982, hereby incorporated by reference, and by reference to U.S. Pat. Nos. 4,073,203; 4,253,348; 4,038,889; 4,226,295; 3,776,048; 4,208,929; 4,039,061; 3,974,720 and 3,942,393, all hereby incorporated by reference.
While the above referenced automatic transmission control systems, and similar systems, are effective to control an automatic transmission by selecting a desired gear ratio which will tend to optimize the fuel economy and/or performance of the vehicle in view of the sensed parameters and then commanding a shift into the selected gear ratio, such control systems were not totally acceptable as the predetermined programs utilized to generate a shift pattern, or patterns, (also commonly referred to as a shift point profile), could not recognize operator selected stable operating conditions of the vehicle and modify the shift patterns generated by the program in response to sensed operator selected stable operating conditions to provide an optimal compromise of fuel efficiency operation and desirable vehicle performance operation.